Coolant loss on diesel
 

Hi guys

I suspect I’m losing coolant somewhere on my 75 tourer auto diesel. I checked last week and the bottle was practically bone dry. I topped up the bottle about half way up the fins in the bottle. I’ve checked it again now and it’s pretty low again. I’ve only done around 100-150 miles since.
Any idea where it could be leaking on these engines?
Thanks.

Thermostat housing is quite common or hoses above gearbox near fusebox can rub through

The little blue O ring on the metal pipe running from the rear of the engine to the thermostat. I’ve had to replace both of mine and had to pressurise the system and shine a torch into the area to find the leak.

Halfway up the fins is a bit much, the system will expel any excess coolant. Remember its an expansion tank not a reservoir. The min and max level markers are right at the bottom of the tank, see below.

https://live.staticflickr.com/65535/...a61d4046_w.jpg

There so also the top hose at both ends the Y that fits to the head, and the other end of the same hose the bend going into the radiator, some times the O-ring fails at that point.

https://i.imgur.com/fY0sRbKl.jpg1

The seals can fail and the part it self sometimes goes brittle over time.
https://i.imgur.com/E6zGrw6l.jpg2

Check the bend where it fits into the rad see if there is any red residue, same at the Y connector .
https://i.imgur.com/FYlINm1l.jpg3

https://i.imgur.com/3imSH55l.jpg4

https://i.imgur.com/acPZPcml.jpg5

https://i.imgur.com/I9Cewxyl.jpg6


Do not forget the coolant tank cap O-rings they can become flat and lose pressure then water can leak from the cap.
https://i.imgur.com/7X8KZZql.jpg7

https://i.imgur.com/dCmbHfMl.jpg8

https://i.imgur.com/pvCdIGCl.jpg9

https://i.imgur.com/FNwNhjBl.jpg10

So a few areas to check

As well as the above, check that it has been tightened fully - I did this out of fear of over tightening the cap, losing all of the coolant in the tank (not to mention the dread and fear of that hot coolant smell when I walked past the front of the car).

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You could take the undertray off and see if it is leaking enough to drip. Mine was from the metal pipe to thermostat mentioned above. Can be seen looking down the drivers side of the engine.

Thank you for all the replies. All advise noted and will investigate soon and report back on my findings.